The present invention relates generally to intravascular catheters. More particularly, the present invention relates to intravascular catheters adapted to treat vulnerable plaque.
Therapy modalities for heart disease have traditionally focused on treating blood vessels which have become occluded (blocked) or stenotic (narrowed) by calcified plaque deposits. Blood vessels that have become occluded or stenotic in this manner may interrupt the flow of blood that supplies oxygen to the heart muscle. Occluded or stenotic blood vessels have been traditionally treated with a number of medical procedures including angioplasty and atherectomy. Angioplasty techniques such as percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA) are relatively non-invasive methods of treating restrictions in blood vessels. During these procedures, a balloon catheter is advanced over a guidewire until the balloon is positioned proximate to a restriction in a diseased vessel. The balloon is then inflated and the restriction in the vessel is opened. During an atherectomy procedure, the stenotic lesion is mechanically cut or abraded away from the blood vessel wall using an atherectomy catheter.
Calcified plaque deposits are typically comprised of hard materials. Plaque, however, may also be comprised of soft materials or combinations of soft and hard materials. Soft plaque is typically comprised of deposits of cholesterol and other fats which build up within the blood vessels as a patient ages. The build up of plaque in the blood vessels is sometimes referred to as atherosclerosis, or hardening of the arteries.
Atherosclerosis often begins as a small injury to an artery wall. This injury triggers a cyclic cascade of injury and response, inflammation, and healing, which may ultimately lead to the narrowing of the artery. As the atherosclerotic plaque worsens, inflammatory cells, especially macrophages, collect at the site to isolate the debris of the damaged tissue. The result is a core of lipid, macrophages or foam cells and nectrotic tissue, covered by a fibrous cap of scar tissue. If the fibrous cap becomes weakened or is subjected to excessive stress, it may rupture, depositing the trombogenic contents of the core into the blood stream. If the resulting blood clot is severe enough, it may occlude the artery. If this obstruction persists in a coronary artery, a myocardial infarction may result.
Plaque deposits that are at risk of rupturing are sometimes referred to as vulnerable plaque. Vulnerable plaque typically comprises a core of soft materials covered with a fibrous cap. Many of vulnerable plaque deposits do not limit the flow of blood through the blood vessels. It is now appreciated that vulnerable plaques that do not limit flow may be particularly dangerous because they produce no warning symptoms, and can rupture suddenly causing a heart attack and death. This may occur, for example, when the vulnerable plaque ruptures and a blood clot is formed inside the blood vessel lumen causing a blockage.
The present invention relates generally to intravascular catheters. One embodiment of the present invention relates to intravascular catheters adapted to treat vulnerable plaque. According to one implementation of the present invention, a catheter for treating a blood vessel having an inner surface and one or more plaque deposits including a core material comprises an elongate shaft having a proximal end and a distal end, a first balloon disposed about a first portion of the elongate shaft for engaging the inner surface of the blood vessel, a second balloon disposed about a second portion of the elongate shaft for engaging the inner surface of the blood vessel, and a first venturi section disposed between the first balloon and the second balloon.